package com.itheima.test02;

import java.util.Scanner;

public class Test_E {
    public static void main(String[] args) {
            Scanner sc = new Scanner(System.in);
            int i = sc.nextInt();
            int number = method(i);
            System.out.println(number);
        }

        public static int method ( int i){
            if (i == 1 || i == 2) {
                return i;
            }
            return method(i - 1) + method(i - 2);
        }
    }
